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What Causes Glaucoma?

Early detection, treatment, and lifelong monitoring of glaucoma are all very important in order to preserve vision.

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Close-up photo of a woman with blue eyes looking up against a green background

What Causes Glaucoma?

Early detection, treatment, and lifelong monitoring of glaucoma are all very important in order to preserve vision.

Glaucoma is a chronic eye disease in which there is damage to the optic nerve. This can affect the vision in many ways; a person may notice blurred patches or blind spots, difficulty with glare, problems with depth perception, and trouble seeing in dim light. Unfortunately, once these changes occur, they are irreversible. Therefore, early detection, treatment, and lifelong monitoring of glaucoma are all very important in order to preserve vision. The good news is that current technology allows doctors to detect changes to the optic nerve at an early stage, before the onset of vision loss or worsening of the disease. There are also effective treatments to lower eye pressure and reduce the risk of further damage to the optic nerve.

There are two main subtypes of glaucoma – primary glaucoma, when there is no identifiable cause, and secondary glaucoma, where there is a known predisposing factor such as injury, or inflammation. There are several theories about the cause of primary glaucoma, and although we don’t know all the answers yet, we have identified several key risk factors:

  1. Elevated eye pressure (this is not the same as elevated blood pressure)
  2. Large optic nerve or thinning of the optic nerve
  3. Closed drainage angle of the eye
  4. Thinner than average cornea
  5. Family history (especially siblings)
  6. Race (open angle glaucoma – African derived and Hispanic derived race; angle closure glaucoma – Asian derived race)

 

Eye pressure can be checked at any eye doctor’s office. Knowing what’s a “normal” eye pressure is not so straightforward though. The average eye pressure is 16 mm Hg, but we know that some people with an average pressure can develop glaucoma, whereas others won’t. This is where the other risk factors really come into play.

Recommendations

  • Get a complete eye exam — which means getting your eyes dilated. Through a dilated exam, we can actually see the optic nerve and assess the size as well as any areas of potential thinning. Some people are born with large optic nerves and will never get glaucoma; but we cannot determine who will and who won’t develop glaucoma over time, hence the importance of a yearly eye exam for those with a large nerve. Family history and race are strong risk factors; if you have a close family member with glaucoma, you should get a screening exam. People of African, Hispanic, and East Asian descent are also predisposed to glaucoma (open versus closed angle) and should get a screening exam.
  • Before the eyes are dilated, I also recommend getting a check of the drainage angle. The cornea thickness can also be measured with a small hand-held device. People with a thinner than average cornea are at greater risk for glaucoma and should be monitored.

 

Glaucoma treatment is one of the fastest growing areas in ophthalmology research and development and the disease management options are improving as time goes on. Our goal is to halt or prevent any further deterioration of optic nerve damage.

 

Article by Mona Kaleem, MD; posted on August 14, 2023

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Mona Kaleem MD 900
Mona Kaleem, MD

Mona Kaleem, MD is an Associate Professor of Ophthalmology at the Wilmer Eye Institute, Johns Hopkins University, in Baltimore, Maryland.

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